Screen streaming has become a popular way for users to share what they see at their own computing devices with users at other devices. The appearance of a desktop or particular application can be recorded and streamed to other users live (e.g., screen sharing) or at a later point in time (e.g., screencasting). In contrast to screenshots, which may only capture the appearance of a computer desktop or application at a particular moment in time, screen streaming can broadcast video of a user's desktop. Moreover, audio can be streamed simultaneously or later synced with a recording to provide improved narrative effect and a richer multimedia experience. As mobile computing devices (e.g., smartphones and tablets) have become more prevalent, screen streaming has spread to these devices. A common in-office scenario, for example, is the streaming of content displayed at a laptop to a larger projection screen.
However, screen streaming can be a risky affair. With live streaming or screen sharing, unanticipated events may cause certain content to be shared unwittingly. For example, a personal or inappropriate email or text message could pop up unexpectedly only to be shared with an unintended audience. Moreover, a user may simply forget that they are sharing their screen and undertake actions revealing personal or secure information. In the case of mobile computing devices, the smaller former factor and personal nature of the device can make a user more likely to forget that content is still being shared when switching between tasks, or moving to a different physical location.